In recent years, researchers have proposed and implemented so called “polar” architectures for the improved transmission of signals. These polar architectures, rather than using complex In-phase Quadrature (IQ) components of a data signal, operate by using the polar components of the data signal. Accordingly, polar implementations of modulation circuitry are used to transmit and receive voice and/or data in the radio frequency (RF) bands of the communications spectrum. Polar implementations have a number of advantages over their IQ counterparts.
However, polar implementations have drawbacks as well. For instance, polar envelope modulation (EM) circuitry typically has no direct visibility of the supply voltage on the envelope modulation driver. Hence, if the supply power is low, such as in low battery situations, for example, then distortion will occur for high envelope power peaks. Moreover, the power amplifier of the envelope modulation circuitry tends to operate in an inefficient range in these situations. This further causes excessive power consumption by the amplifier, which exasperates the low supply power and/or low battery condition.
Some attempts have been made to solve this problem. For instance, some researchers have attempted to solve the problem by first determining situations in which a low battery condition is to be generally expected. Then, for these situations, a margin of power reduction is built into the supply power of the transmitter design. The power reduction margin lowers the nominal output power Pout, which reduces communication coverage and corresponds to lower service quality.